Approximately 25,000 newborn infants succumb in the United States each year, because of the idiopathic respiratory distress syndrome. Although prematurity is the most frequent clinical factor associated with this disease entity, intrauterine asphyxia is generally accepted as another predisposing factor - and one that might be more amenable to therapy. The mechanisms by which intrauterine asphyxia predisposes to this syndrome are unknown. But there is convincing evidence that it can cause pulmonary edema immediately after delivery, which gravely impairs newborn respiration. The objectives of this study are to determine: 1. the mechanisms by which asphyxia promotes pulmonary edema in the newborn, as well as 2. the pulmonary ventilatory and circulatory consequences of these asphyxial events.